2 A I®  L A B S


Designing Light for Skin and Eye

Tim Barber, Director of Machine Cognition, 2AI Labs.
Mark Changizi, Director of Human Cognition, 2AI Labs.


A wide variety of industries specialize in technologies that shape the spectrum of light reaching the eye from the environment; two significant examples are artificial illuminants (including traditional bulbs and LED light sources) and filtered lenses (including windows and eyewear).

Technologies of this kind can work effectively only by designing for the color vision humans actually possess. This, in turn, requires understanding the evolutionary design and function of color vision. Although key aspects of the mechanisms of color vision have long been understood, only recently has a major advance been made concerning its evolutionary function.

2AI is the intellectual source for this seminal discovery, which is that color vision is optimized for sensing the spectral modulations occurring on the bare skin of other people, providing the viewer with information about the other person's state, emotion, mood and health. The spectral modulations on skin are mediated by changes in the nature of the underlying blood, in particular by modulations to the concentration and oxygenation of hemoglobin.

Via comprehension of the hemoglobin spectrum underlying skin color signals and the visual mechanisms designed to detect them, 2AI's technology selectively enhances or attenuates the spectral signals to achieve various desired effects.

  1. Everyday amplification of color vision. Human color vision evolved for use in our regular, everyday, highly social lives. Although our color mechanisms are well optimized for sensing human skin signals, it is possible to significantly enhance our sensitivity by appropriately designed filters. Such technology, whether used in artificial lighting or sunglasses, has applications for everyday use -- it further amplifies the color signals we evolved to sense in our daily lives.

  2. Special-purpose amplification of skin signals. Although amplification of our ability to sense skin color signals has use in the course of our normal lives, it is especially useful in a number of special domains.

    1. General amplification: Technology which amplifies our ability to sense skin color signals -- and the emotions, moods, states or health they indicate -- has applications in several domains, including health (hospital, home, and in the field), law enforcement, sports and games (e.g., poker), and dating.

    2. Magnifying blood concentration: It is possible to design an appropriate filter that destroys one of the two dimensions of color modulation (the oxygenation modulation), but magnifies the remaining dimension, concerning the concentration of hemoglobin under the skin. Here there are significant health applications (e.g., sensing internal bleeding).

  3. Attenuation of skin signals. By understanding the mechanisms underlying our ability to sense the spectral changes occurring in skin, it is possible to design a filter to attenuate or eliminate sensitivity to those signals. A major application here is in cosmetics (e.g., salons, dressing rooms, restaurants and night clubs): lighting can be designed to attenuate the visibility of acne, rosacea, surface vessels and other irregularities due to modulations in the concentration of blood under the skin.

With a grasp of what color vision is for -- it is, more briefly, for seeing human skin and the signals it displays, via the mechanism of blood physiology modulations -- these new kinds of technologies suggest themselves. 2AI has unique expertise in designing light for human eyes, and possesses intellectual property behind new technologies with applications within a number of industries.